<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div class="list" style="display:flex ; text-align:center;">

    </div>
    <button class="prev">上一页</button>
    <button class="next">下一页</button>
    <span class="s1">1</span>
    <span class="s2">/</span>
    <span class="s3">4</span>
    <script>

        var page = 1;//保存当前页码

        //将对象格式转为查询字符串格式
        function objToSearchString(obj) {
            var str = '';
            //遍历对象, 将对象obj的每个属性名和属性值拼接为 key=value& 的格式
            for (var key in obj) {
                str += `${key}=${obj[key]}&`
            }
            //返回拼接好的字符串  key=value&key=value&key=value&key=value
            return str.slice(0, str.length - 1);
        }

        function ajax(method, url, params, cb) {
            //--------------------------------------------------------------1.创建请求对象
            var xhr = new XMLHttpRequest();

            //--------------------------------------------------------------2.配置请求对象
            xhr.open(method, url + "?" + objToSearchString(params));

            //--------------------------------------------------------------3.设置回调函数
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4) {
                    cb(JSON.parse(xhr.responseText));
                }
            }

            //--------------------------------------------------------------4.发送请求
            xhr.send();
        }


        //默认上一页按钮禁用
        document.querySelector('.prev').disabled = true
        //默认显示第一页的10个表情
        if (document.querySelector('.prev').disabled) {
            ajax('get', `https://yantianfeng.com/api/emotion`, { page: page, count: 10 }, function (data) {
                // console.log(data);
                var str = data.emotions.map((item, index) => {
                    return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                }).join('')
                //渲染表情
                document.querySelector('.list').innerHTML = str;
            });
        }



        //点击上一页, 获取上一页的表情,渲染表情
        document.querySelector('.prev').onclick = function () {
            //启用下一页按钮
            document.querySelector('.next').disabled = false
            document.querySelector('.s1').innerHTML = page - 1
            // console.log(page);
            if (page > 1) {
                ajax('get', `https://yantianfeng.com/api/emotion`, { page: --page, count: 10 }, function (data) {
                    // console.log(data);
                    var str = data.emotions.map((item, index) => {
                        return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                    }).join('')
                    //渲染表情
                    document.querySelector('.list').innerHTML = str;
                });
            }
            //如果是第一页，禁用上一页按钮
            if (page == 1) {
                document.querySelector('.prev').disabled = "true"
            }
        }

        //点击下一页, 获取下一页的表情,渲染表情
        document.querySelector('.next').onclick = function () {
            //启用上一页按钮
            document.querySelector('.prev').disabled = false
            document.querySelector('.s1').innerHTML = page + 1
            // console.log(page);
            if (page < 4) {
                ajax('get', `https://yantianfeng.com/api/emotion`, { page: ++page, count: 10 }, function (data) {
                    // console.log(data);
                    var str = data.emotions.map((item, index) => {
                        return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                    }).join('')
                    //渲染表情
                    document.querySelector('.list').innerHTML = str;
                });
            }
            //如果是最后一页，禁用下一页按钮
            if (page == 4) {
                document.querySelector('.next').disabled = true
            }

        }



        //ajax('get','https://yantianfeng.com/api/sdfsd');

    </script>
</body>

</html>